For as long as I've been reading "How to" books for wargames terrain they've been referring to a mythical substance called "insulation tiles". These foam tiles apparently make the best foundation for terrain as they are light, high-density (hence strong and impact-resistant) and they can be shaped really well.
The problem was, nobody I ever spoke to seemed to know where to get them in Australia. I couldn't find them at Bunnings, model shops, anywhere. A bit of Google-fu revealed that the substance is extruded polystyrene but the only supplier I could find was in Melbourne and they don't ship it. And I really wanted it to make hills for my 6mm terrain set...
Well, I now have a whole bunch of it thanks to a red-hot tip from the Esteemable John H. Steed, Esq. He had also tried and failed at Bunnings but had "heard you might be able to get it at Just Rite in Fyshwick." Mate, you were spot on. When I went out there today the girl behind the counter knew exactly what I wanted it for - "Modelling, right?" Turns out it's called Blueboard or Isoboard in the trade and you buy it in 2400mm x 600mm x 25mm sheets.
And it's every bit as good as the books say - better to carve, better to sand, and as strong as anything. Stand by for piccies and a tutorial on the hills in the coming days!